Disk files, also referred to as disk drives are information storage devices which utilize a rotatable disk with concentric data tracks containing the information, a head or transducer for reading or writing data onto the various tracks, and an actuator connected to a carrier for the head for moving the head to the desired track and maintaining it over the track centerline during read or write operations. There are typically a plurality of disks separated by spacer rings and stacked on a hub which is rotated by a disk drive motor. A housing supports the drive motor and head actuator and surrounds the head and disk to provide a substantially sealed environment for the head-disk interface. In conventional magnetic recording disk files the head carrier is an air-bearing slider which rides on a bearing of air above the disk surface. The slider is urged against the disk surface by a small force from a suspension which connects the slider to the actuator, so that the slider is in contact with the disk surface during start and stop operations when there is insufficient disk rotational speed to maintain the air bearing. A lubricant is required on the disk surface to prevent damage to the head and disk during starting and stopping of the disk file.
The conventional magnetic recording disk file suffers from several disadvantages which are due to the air-bearing head-disk interface. The spacing between the head and disk is limited by the minimum achievable flying height of the air bearing slider, which means the recording performance of the disk file, which is directly related to this spacing, is accordingly limited. When the slider has been in stationary contact with the disk for a relatively short period of time, the liquid lubricant and the relatively large air-bearing surface of the slider create static friction (or "stiction") forces which cause the slider to stick to the disk surface, which can result in damage to the head, disk or suspension when the slider breaks free from the disk at start up of the disk file. The interface, which is primarily a thin film of air when the disk file is operating, provides very little stiffness between the head and disk so that the disk file is very sensitive to vibration and impact, which makes the conventional disk file undesirable for certain applications, such as use in a portable computer. The air required inside the disk file to support the air-bearing slider also increases the air drag on the rotating disks, thereby increasing the power consumption, contributes to the noise level in the outside environment, causes buffeting of the suspension, and increases the corrosion and oxidation of the heads, disks and electronic components.
There are several references which describe different types of head carriers and liquid bearings as possible alternatives to the conventional air-bearing head-disk interface in magnetic recording disk files. In assignee's U.S. Pat. No. 2,969,435, a sled-type transducer carrier with a large flat surface rides on a layer of oil on the disk, the oil being supplied from an oil reservoir external to the disk file and discharged from a nozzle located ahead of the carrier. In assignee's pending application, U.S. Ser. No. 264,604, filed Oct. 31, 1988, and published May 9, 1990 as European published application EP 367510, a disk file utilizes a continuously recirculating low viscosity liquid lubricant, which is maintained as a relatively thick layer on the disk, and a transducer carrier which has triangular shaped feet to plow through the low viscosity liquid layer. The EP reference suggests that if the disk file is hermetically sealed with no air present the low vapor pressure lubricant can evaporate which allows the required recirculation of the lubricant to occur by distillation.
What is needed is a disk file with a liquid bearing interface which provides minimal head-disk spacing and which does not require continuous recirculation of the lubricant.